Additional strains of Aedes aegypti mosquitoes will be compared with the competent Santo Domingo strain (as a control) for vector competence. Included in the study will be two genetically characterized and sympatric populations from East Africa, one being endophilic-anthropophylic and the other exophilic-zoophilic. Strains from Asia and the southern United States will be studied in vivo and in vitro using per os feeding through membranes as well as parenteral inoculation. ELISA and RIA will be applied to the serological diagnosis of Crimean hemorrhagic fever-Congo virus infections. To minimize biohazard in handling large volumes of infected cell culture fluids, methods to inactivate CHF-C virus prior to harvest of fluid, or use of Hazara virus as a substitute for CHF-C virus will be explored. Radiolabeled cytoplasmic extracts from infected CER cells will provide reagents for RIA and for analyses of proteins by polyacrylamide gel electrophoresis. The RIA and PAGE analyses will be used to determine if geographic strains of CHF-C virus differ in their protein or antigenic make-up.